Method of making a heat exchanger



Oct. 2, 1962 H. M. CAMPBELL METHOD OF MAKING A HEAT EXCHANGER 3 Sheets-Sheet 1 Original Filed June 2. 1955 INVENTOR. flan 714V fwfazu FIGJ.

Oct. 2, 1962 H M, CAMPBELL 3,056,189

METHOD OF MAKING A HEAT EXCHANGER ori inal Filed June 2, 1955 s Sheets-Sheet 2 s .23 i 1 f 1, I a i l l 5 I I i 2e L 6 I I I v l I l 1 I I l I INVENTOR.

Oct. 2, 1962 H. M. CAMPBELL METHOD OF MAKING A HEAT EXCHANGER 3 Sheets-Sheet 3 Original Filed June 2, 1955 m In 0 I I a .l"i"l llllllllllllllll us INVEN T OR. A wru M [flMPBfLL 3,056,189 Patented Oct. 2, 1962 thee 3,056,189 METHUD Gil MAKING A HEAT EXCHANGER I-Iuntly M. Campbell, Alton, Ill, assignor to ()lin Mathieson Chemical Corporation, East Alton, lit, a corporation of Virginia Original application Tune 2, i955, Ser. No. 512,655, now Patent No. 2,957,679, dated Get. 25, 1960. Divided and this application Sept. 18, 1958, Ser. No. 765,692

3 9 Claims. (till. 29-1573) This invention relates to a heat exchanger of the multiple parallel tube type as exemplified by automobile radiators, and is an improvement upon the heat exchanger disclosed in the copending application of myself and Leland H. Grenell, Serial No. 175,226, filed July 21, 1950, now Patent No. 2,759,247.

This application is a division of co-pending application Serial No. 512,655, filed June 2, 1955, now Patent No. 2,957,679 issued October 25, 1960.

In the aforesaid application of myself and Leland H. Grenell, there is disclosed a heat exchanger wherein a plurality of separate panels, each made from pressure unified sheets of metal so as to include integral tubes and intervening webs, are arranged together in aligned spaced series, and secured in such relationship by appropriate interconnecting parts. In the aforesaid Wilkins application, it is contemplated to integrate a plurality of panels into one continuous plate, and then to zig-Zag fold the plate so that each tube panel constitutes a lap of the fold, and the structure is held together in the appropriate spaced relationship by integral parts of the single plate. The structures disclosed in said applications, and all other such comparable constructions of which I am aware, require the provision of a separate header tank at each end of the tube panels, and connected to the various tubes by an appropriate fluid-tight connection, such as a soldered joint. While the structures disclosed in said applications represent a substantial diminution of" the amount of soldering required for assembling a heat exchanger of the character contemplated, it is obviously desirable, and hence it is an object of the present invention, to further eliminate the necessity for such soldering, or other fluid-tight connections, between the tubes and the header tanks, or chambers, of either end thereof.

The aforesaid objective is accomplished in accordance with the present invention by providing, as an integral part of the pressure unified sheet from which the several tube panels are formed, a transverse header chamber connected with the various tubes in the panels, and which is, like the integrally connected tube panels of the aforesaid Wilkins application, zig-zag folded to form a continuous serpentine header chamber at the opposite ends of the tube panels.

Another object of the invention is to provide a heat exchanger of the character aforesaid, wherein the shape of the tubes is such as to be readily adaptable for the reception and retention of corrugated fin stock between adjacent panels of the folded structure.

Other objects will become apparent from the following description when read in connection with the accompanyin g drawings, in which:

FIGURE 1 is a plan view of a pressure unified plate containing an internal pattern of unconnected areas suitable for the manufacture of the heat exchange member shown in the other figures of the drawings;

FIGURE 2 is a view in front elevation of an automobile radiator embodying the heat exchange member of the present invention;

FIGURE 3 is a top plan view of the radiator shown in FIGURE 2, part being broken away, and part shown in section to reveal the relationship of the parts;

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 2;

FIGURE 5 is a sectional view taken of FIGURE 2; and

FIGURE 6 is a perspective view of a portion of the plate shown in FIGURE 1 after the same has been distended, but before folding.

in accordance with this invention, a heat exchange unit with an array of tubes arranged in spaced substantially parallel planes is fabricated from a plate of metal formed of two sheets pressure welded or single phase roll welded together with an intervening pattern of stopweld material delineating areas in which fluid passageway will be distended by pneumatic or hydraulic expansion. The plate includes not only a series of heat transfer fluid conveying tubes, but also an inlet header passageway and an outlet header passageway. The plate is folded back and forth to provide a series of panels containing the heat transfer tubes. The distended plate from which the unit is made includes two walled distended separation portions defining fluid passageways in the sheet, and also includes welded single walled portions, or unseparated areas, of double thickness as a unitary or monolithic portion of the sheet. The folds of the plate occur at certain of the relatively thick welded single walled portions between panels so as to provide a pleated structure made up of folded areas alternating with tubed panel portions between folds. Elongated unwelded portions in each panel form the heat transfer tubes and these elongated unwelded portions of the panels are formed coextensively at their extremities with transversely extending unwelded portions which form the inlet and outlet header portions which extend across the entire zig-zag folded sheet. Between the heat transfer tubes, the plate is perforated at least at the regularly occurring bends so as to allow a cross stream of fluid, such as air, to pass along the outside of the heat transfer tubes disposed in the panels of the sheet between folds. Each panel may contain a single tube or a number of parallel spaced individual smaller tubes. The opposing walls at the distended tube and passageway portions may be internally welded together at intervals for the purpose of stiffening these portions. While the heat exchange unit of this invention is adapted to constitute an entire heat exchanger, two or more of the units may be assembled to make up a heat exchanger. Since the tube panels are adapted to be set up in spaced substantially parallel relationship, it is desirable that any suitable finstock, preferably corrugated, be installed between the panels in contiguity with the heat transfer tubes.

The heat exchanger structure of this invention is further characterized by the fact that the walls of the header passageways, or inlet and outlet channels, are distended out beyond the surfaces of the unseparated areas of the plate to a greater degree than the distended walls of tube passageways of the tube panels. As a result, the crosssectional area of each of the header passageways is considerably larger than the cross-sectional area of a tube passageway. This enables the header portions in adjacent panels of the zig-zag plate to be in abutment, thus producing a more solid construction while the tubes of -adja cent tube panels remain spaced to form an open passage for other fluids, such as air, between the spaced panels.

' It is preferred that the cross-sectional shape of at least the tube passageways in the panels be substantially flat and oblong. In the specific embodiment hereinafter described, both the tube passageways extending down each panel and the header passageways extending transversely across the opposite ends of the panels are of flat oblong shape, which adapts the unit for advantageous assembly with all its portions, including the header sections as well as the fin stock. A flat oblong passageway cross-section along line 55 is made practical by the inclusion of the areas of internal reenforcement, and such oblong shape is peculiarly adapted for inclusion of fin stock.

The heat exchange unit consists of elongated tube panels disposed between bent panel interconnecting portions, or folds, formed integrally with the panels. Each panel comprises a portion of a header chamber at each end of the panel and also includes at least one tube passageway forming a fluid connection between the header portions. Each fold or panel interconnecting portion is of elongated configuration, too, and is disposed between the elongated edges of a pair of adjacent panels. Each fold comprises at each end a bent or arcuate portion of a header passageway, and between the header portions each panel interconnecting fold of the zigzag sheet is perforated with slots, preferably elongated to permit the free passage of a fluid, such as air, over the outside of the walls of the heat transfer tube passageways of the panels. This leaves between each adjacent pair of slots in the fold a bent interconnecting strap between adjacent panels. Thus each header is of serpentine configuration, and consists of a series of the header passageway portions disposed at one end of each of the panels in alternation with a series of the arcuate header passageway portions disposed at the same end of each of the panel interconnecting folds.

The heat exchange unit, especially when it is formed of very thin gage metal, is advantageously mounted in a confining frame, such as one of sheet metal of heavy gage. The frame may be provided with mounting brackets, or the like, by which the unit may be cradled or supported in a desired heat exchange installation.

The plate shown in FIGURE 1 is produced from two sheets of metal 1 and 2 which have been pressure unified by the technique disclosed in United States Patent No. 2,690,002 to L. H. Grenell, with a pattern of stop-Weld material between them. The patern of stop-weld material is indicated by the stippling of FIGURE 1, and embraces a plurality of parallel elongated areas 3 intervened by unprotected areas 4. The pattern of stop-weld material also includes transverse header regions 5 and 6 across the tops and bottoms, respectively, of all of the elongated areas 3. The pattern of stop-weld material in one of the header regions extends completely to the margin of the plate as shown at 7, but otherwise, the pattern of stop- Weld material is completely surrounded by a marginal area 8 unprotected by the stop-weld material. Within the several elongated areas 3, there are islands 9 unprotected by the stop-weld material, and likewise within the header regions 5 and 6, there are islands 10 unprotected by the stop-weld material. The plate shown in FIGURE 1 is shown in the condition in which it exists after the two sheets 1 land 2 with the intervening pattern of stop-weld material has been subjected to a rolling operation in which the sheets are reduced in thickness, elongated in length, and integrated at all of the areas 4, 8, 9 and 10, which are unprotected by the stop-weld material.

The plate shown in FIGURE 1 is inflated by the introduction of fluid under pressure through a suitable inflation tool inserted at the marginal exposure 7 of the pattern of stop-weld material. Such inflation distends the plate and forces the respective sheets 1 and 2 thereof apart at all areas which were protected by the pattern of stopweld material, producing open channels thereat, and resulting in a structure such as that shown in part in FIG- URE 6, wherein the areas delineated by the elongated strips 3 of stop-weld material have become tubes13; the area delineated by the transverse header region of stop weld material 5 has become header chamber 15; and the area delineated by the stop-weld material 6 has become header chamber 16, while the sheets 1 and 2 remain integrated at the several areas which were unprotected by stop-weld material, to wit: 4, 8, 9, and 10. The integrated areas last mentioned in the distended plate become webs 14, ribs 18, and islands 19 and 20.

Either before or after distention of the plate as aforesaid, a series of openings 21 may be formed in the respcctive webs 14 for the purpose hereinafter described.

Either before or after the plate has been distended as aforesaid, but preferably after the openings 21 are formed therein, the plate shown in FIGURE 1 may be Zig-zag folded along the center lines of webs 14 to produce panels, each containing a tube 13 and the part of the header chambers 15 and 16 which are adjacent the ends of the corresponding tube 13. Such a zig-Zag folded structure is shown clearly in FIGURES 2 and 3. Each lap of the folded structure constitutes a panel embracing a part of the length of header chambers 15 and 16, as well as one or more tubes 13 which extend from that part of the header chambers embraced by that panel. The header chamber 15, as clearly shown in FIGURE 3, is continuous from panel to panel, and is of serpentine shape. As shown in the drawings, the pitch of the folding of the plate is such that the header portions of each panel are exteriorly contiguous with the header portions of the next panel, thus producing a structure which is not only compart, but which, by virtue of the contiguity mentioned, is structurally strong when held together by suitable confining members hereinafter to be described. In order to avoid the pinching off of the header chambers when the structure is zig-zag folded, the plate may be zig-zag folded before distention, and thereafter inflated to the extent necessary to bring the exterior walls of the header portions into contiguity with each other. Where it is desired to distend the plate before folding, it is preferable to confine the plate between members shaped to produce a series of corrugations 22 in the walls of the header chamber portions which will constitute the inside radius at the 'bight of the several folds. It is, however, preferred to utilize a combination of the two procedures just mentioned, that is to say, the plate is partially distended before folding, and then the distention is completed after folding. For example, the initial distention may be to an extent such that the tube portions 13 are completely distended, and the header portions 15 and 16 are distended only to the same degree as the tube portions, the latter, after folding, to be more fully distended.

It is preferred that the tube portions 13 be of oblong cross-section with the separation between opposite Walls thereof substantially less than the separation between opposite walls of the header chamber. In this way, the adjacent laps of the header chamber may be brought into contiguity without bringing the exterior walls of the tube portions into contiguity, so that an appropriate space for the circulation of a heat exchange medium, such as air, between the tube portions of the respective panels is maintained.

The provision of the islands 19 within the confines of the respective tube panels tends to induce the oblong overall cross-sectional shape of the tubes, as well as to stiffen and strengthen the tube portions of the respective panels, and to divide the stream of water or other coolant traversing such tubes into smaller streams. Similarly, the islands 20, at which the header portions are integrated, tend to eliminate non-uniformity in the degree of distention of the header chambers from one panel to the next, and to strengthen and stiffen the header chambers of each panel.

In FIGURE 4, a sectional view is shown through the portions of the serpentine header where the islands 20 are located, it being understood that the header chamber is open both above and below the section shown. The section shown at the lefthand end of FIGURE 3 is, however, taken below the region of islands 20, so that the chamber 15 is there shown to be completely open.

In the sectional view shown in FIGURE 5, which is taken at three different levels through the tube portion of the panels, the leftmost pair of panels are shown at a section through the islands 9; the middle pair of panels are shown at a section between the islands 9 and the residue of web 14 which is left upon forming the openings 21; and the rightmost pair of panels are shown at a section through the residual metal vertically between openings 21.

Suitably secured in one endmost lap of each header chamber 15 and 16, there is an appropriate fitting 23. The fittings 23 may be secured to the zig-Zag folded plate structure in any suitable manner, as by soldering, it being preferred to attach the fitting to the upper header at the diagonally opposite corner of the structure from the point of attachment of the corresponding fitting to the lower header.

While, in the foregoing description, reference has been made to, and the drawings specifically show, the header chamber 15, it will be understood that the header chamber 16 is identical, except that it is upside down with respect to the tubes 13.

Either before or after the plate is completely distended, but after it is at least partially zig-zag folded, suitable fin stock may be inserted between the respective tube panels, as shown at 24. Such fin stock may be corrugated or Zig-zag folded in a manner customary in the art, and disposed between the panels in such manner as to present edges athwart the direction of transverse air flow through the air space between the panels.

Upon completion of the distention and zig-zag folding of the plate structure, the same may be enclosed within a suitable confining frame 25 which may have lugs 26 appropriately situated for connecting the same in the desired relationship upon the machine in connection with which the heat exchange member is to be used.

From the foregoing description, those skilled in the art should readily understand the construction and operation of the radiator core and realize that it accomplishes the objects of the invention. While the invention has been described in detail with respect to its use as the core of an automobile radiator, it will be readily understood that as a heat exchanger it is adapted to divers other uses; and while reference has been made to the circulation of liquid through the tubes, and to be transverse passage of air through the spaces between the tube panels, it will be readily understood that other coolant fluids will, under various circumstances, be utilized instead of air or water, or both.

While a complete disclosure of one embodiment of the invention has been given to illustrate the construction and operation of the same, it is not to be understood that the invention is limited to the details of the foregoing disclosure. On the other hand, those skilled in the art will readily understand that the essential features of the present invention may be adapted and applied in other forms, and hence such adaptation and application as does not depart from the spirit of the invention is contemplated by and within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

l. The process of fabricating a longitudinally corrugated heat exchanger having a plurality of spaced folds interconnected in a serpentine manner by return bends at alternately adjacent ends from a blank comprising providing in said blank a plurality of parallel spaced tube circuits interconnected to each other at adjacent ends by a common header tube extending in a direction transverse to said tube circuits with said tube circuits and said header tube bulged out of said blank an equal amount, reversely folding said blank between said tube circuits .to provide a corrugated structure with the folds thereof containing said tube circuits in parallel and spaced relationship to each other, inflating only said header tube to sufficiently outwardly distend adjacent par allel portions of said blank containing said header tube an additional amount to bring said parallel portions into abutting relationship with each other while maintaining said spaced relationship between said tube circuits, and attaching a tubular fitting to and in communicating relationship with said header tube adjacent each of the said ends of said tube circuits to adapt said heat exchanger in operation for circulation of a heat exchange fluid through said tube circuits and the said header tube interconnected to said tube circuits.

2. A process of fabricating a corrugated heat exchanger having a plurality of spaced folds interconnected in a serpentine manner by return bends at alternately adjacent ends comprising interposing a pattern of weldinhibiting material between superposed sheets to define a plurality of spaced tube circuits interconnected to each other at adjacent ends by a common header tube extending in a direction transverse to said tube circuits, welding said sheets together in their adjacent areas not separated by said material to form a unified plate, inflating with fluid pressure the unwelded portions in said plate defined by said tube circuits and said header tube to distend said unwelded portions an equal amount outwardly of said plate, corrugating said plate by reversely folding between said tube circuits to provide a plurality of folds in parallel and spaced relationship to each other, further sutficiently outwardly inflating only the unwelded portions in said plate defined by said header tube to a greater extent than said tube circuit while maintaining said spaced relationship between adjacent portions of said folds between said tube circuits, said further inflation being sufiicient' to distend adjacent portions of said plate containing said header tube into abutting relationship with each other and attaching a tubular fitting to and in communicating relationship with said header tube to adapt said heat exchanger in operation for circulation of a heat exchange fluid through said tube circuits and the said header tube interconnected to said tube circuits.

3. The process of claim 2 wherein said interposed pattern includes a plurality of islands free of said material disposed at spaced points in said tube circuit and in said header tube.

4. A process of fabricating a corrugated heat exchanger having a plurality of spaced folds interconnected in a serpentine manner by return bends at alternately adjacent ends comprising interposing a pattern of weldinhibiting material between superposed sheets to define a plurality of spaced tube circuits interconnected to each other at adjacent ends by a common header tube extending in a direction transverse to said tube circuits, welding said sheets together in their adjacent areas not separated by said material to form a unified plate, in flating with fluid pressure the unwelded portions in said plate defined by said tube circuits and said header tube to distend said unwelded portions an equal amount outwardly of said plate and simultaneously corrugating transversely across portions of said plate containing said header tube which will subsequently constitute the inner radius of the bight between adjacent folds, corrugating said plate by reversely folding between said tube circuits to provide a plurality of folds in parallel and spaced relationship to each other further sufl-lciently outwardly inflating only the unwelded portions in said plate defined by said header tube to a greater extent than said tube circuit while maintaining said spaced relationship between adjacent portions of said folds containing said tube circuits, said further inflation being sufficient to distend adjacent portions of said plate containing said header tube into abutting relationship with each other, and attaching a tubular fitting to and in communicating relationship with said header tube to adapt said heat exchanger in operation for circulation of a heat exchange fluid through said tube circuits and the said header tube interconnected to said tube circuits.

5. The process of claim 4 wherein said unwelded portions are distended into a flat Oblong configuration.

6. The process of claim 5 including the step of slotting the return bends between said first and second patterns and parallel to said tube circuits.

7. The process of claim 6 including the step of inserting corrugated fin stock between spaced portions of said folds and contiguous with said tube circuit.

8. A process of fabricating a corrugated heat exchanger having a plurality of spaced folds interconnected in a serpentine manner by return bends at alternately adjacent ends comprising interposing a first pattern of stop-weld material between superposed sheets adjacent one pair of adjacent ends of said sheets, interposing a second pattern of stop-weld material between said sheets adjacent a pair of adjacent ends opposite said first pair, interposing a third pattern of stop-weld ma terial defining a plurality of spaced tube circuits extending from said first pattern to said second pattern, Welding said sheets together in their adjacent areas not separated by said material to form a unified plate, distending the unwelded p rtions in said plate an equal amount by injecting therein a fluid pressure and simultaneously cormgating transversely portions of said plate containing said first and second patterns which will subsequently constitute the inner radius of the bight between adjacent folds, reversely folding said plate between said tube circuits to provide folds in parallel and spaced relationship to each other, further sufiiciently outwardly distending with fluid pressure only the unwelded portions in said plate defined by said first and second patterns an additional amount to bring the last said portions of said plate into abutting relationship with each other While maintaining said spaced relationship between remaining portions of said plate containing said third pattern, and attaching a tubular fitting to the distended unwelded portion defined by said first pattern and to the distended unwelded portion defined by said second pattern to adapt said heat exchanger in operation for circulation of a heat exchange fluid through the distended unwelded portions defined by said first pattern, said second pattern and said third pattern.

9. The method of claim 8 wherein said first, second and third patterns include a plurality of islands free of said material disposed at said points in said patterns.

References Cited in the file of this patent UNITED STATES PATENTS 2,690,002 Grenell Sept. 28, 1954 2,779,173 Wurtz Jan. 29, 1957 2,845,695 Grenell Aug. 5, 1958 2,848,200 Jacobs Aug. 19, 1958 2,850,793 Schweller Sept. 9, 1958 2,884,768 Gould May 5, 1959 2,924,437 Wilkins Feb. 9, 1960 2,926,003 Pulsifer Feb. 23, 1960 FOREIGN PATENTS 673,311 Great Britain June 4, 1952 

